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Discussion Starter · #1 ·
I just sold my Sabre 1100, the buyer sent me a text after his 30 mile commute home showing the overflow spit out of coolant (its clear it came from overflow).
I have never had this happen. I have not added coolant in a long time. Level was just below upper mark.
I have not ridden for about 1 month.

Temps have been cold here...avg 30degrees.
Today is 38.

So, given all that, and a 30 mile ride after sitting for 1 month, in temps of 38 degrees.
Is this somewhat common?

I mean, I have a buyer now thinking I sold a dud/problem bike and here I am sitting thinking damn, how could this just NOW be a problem?

any ideas?
The pic he sent me just now:
Tire Wheel Grille Automotive tire Hood


here is my last known check (about 1 month ago) before my last 30 min ride and no sign of spit out in my garage.
I put a red line on the upper mark for easy eyeballing the level.

Wheel Automotive lighting Hood Automotive tire Motor vehicle
 

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Discussion Starter · #2 ·
Or can killing the power and engine (via key) vs killing engine via kill switch and then power moments later....giving some time for fan to do its job to cycle the coolant to proper places?


I am just perplexed WHY this happened. Its so odd for the new buyer to experience this.
 

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1983 Honda vt750 Shadow
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20,327 Posts
If the radiator cap rubber seals are not sealing perfectly for the return system, the coolant can be pushed into the overflow like they should but not be returned to the radiator when it cools down.
So it increases in the tank and my be what happened when it got hot again and the radiator built up pressure.
Blew out the overflow.
Changing the cap may be the solution.
 

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1996 Honda Shadow VT1100-C2
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229 Posts
Automotive tire Hood Automotive lighting Automotive exhaust Asphalt
Tire Wheel Land vehicle Fuel tank Vehicle


In for answers. Mine does this too although I may have had an overheating problem before I had the carburetor redone and right now I know I have an electrical problem because occasionally some of my lights go out and the radiator fan does not come on when it should sometimes it won't even come on when I flip my manual bypass switch which should immediately ground it bypassing the temperature sensitive switch.
 

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1995 VT1100C2
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4,843 Posts
It would be interesting to see a photo similar to your second photo showing where the coolant level is now. Seems odd to just spit out coolant unless refilled or rad cap not tightened etc.
 

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2009 Shadow Spirit 750
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551 Posts
Curious... what were the environmental conditions when this happened to the bikes? (ambient air temp, etc)
Only time I've ever had that happen was on my last Shadow (07)... and was coming back cross country from Sturgis SD for the Rally in the end of Summer heat coming down out of the Black Hills. But it only sent a small amount of coolant to the pavement when stopped. And on my 09, never even got it hot enough to have the fan kick on. I've tested to make sure it does work though. But I haven't had this happen with it and I've ridden it everywhere over the last 5 years.
 

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1996 Honda Shadow VT1100-C2
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229 Posts
For me, it happened as soon as I bought the bike at the end of July 2022, in hot weather. But this is well-used 27-year-old motorcycle with an unknown amount of miles on it. But The bike had carburetor issues and may have been running lean and too hot in fact I know it was running too hot at certain times because the red temperature light came on although I'm not sure if that was caused by the loss of coolant first. (I hate that there's no way to see when your coolant is spewing out the overflow tube as you're riding you can only keep an eye on it when you stop and lean way over and look down.)

Then After I got the carburetors rebuild cleaned re-jetted, the bike ran great. Although I have no way of sensing the temperature (footnote 1) now in the winter I've ridden it several times in cold weather (40's Fahrenheit) November through now, January, and I've only seen it dump coolant from the hose one time and that's when I know my radiator fan quit working.
 

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1996 Honda Shadow VT1100-C2
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229 Posts
Footnote 1:
I have tried use a noncontact laser thermometer on various parts of the engine,
but I get inconsistent reading so I don't trust the numbers I'm getting. In any case, I have not used that device yet since the carburetors got rebuilt and I will do the test in the future, checking the same parts of the cylinder head covers and the inside edge of the tail pipes and comparing today's numbers to what they were four months ago before the carburetor work.

Also, in an attempt to find out if my motorcycle was overheating I bought a new radiator cap that has a built-in thermometer which has a little brass probe that extends down about 3/4 of an inch into the radiator neck. However unless my radiator is 100% full this probe does not actually contact the hot liquid and when it's not touching the coolant it is not accurate.
And, it's impossible to see while you're riding in order to check this radiator caps built-in dial I have to pull over lean way to one side and try to put my head in a proper position for viewing without my helmet knocking my right side mirror out of alignment.

Automotive tire Automotive lighting Motor vehicle Gauge Tire
 

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1996 Honda Shadow VT1100-C2
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I had this happen a lot on my 1988 vt1100. The bike would get hot and finally realized the fan wasn't turning on till after coolant was spewing out. Decided to do trial and error and bought a new temperature switch, which ended up solving the problem.

I may do that in the future. For now I solved the electrical issue with the radiator fan by installing a new grounding toggle switch which bypasses the temperature-sensitive switch that would connect the circuit through the ground (or negative) side.
 

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I may do that in the future. For now I solved the electrical issue with the radiator fan by installing a new grounding toggle switch which bypasses the temperature-sensitive switch that would connect the circuit through the ground (or negative) side.
I had ended up doing the same before replacing the switch. Found the switch on amazon for something around 8 bucks. Easy and quick switchover too, and it solved the problem.
 
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